def fib2(n): # return Fibonacci series up to n
        """Return a list containing the Fibonacci series up to n."""
        result = []
        a, b = 0, 1
        while a < n:
            result.append(a)    # see below
            a, b = b, a+b
        return result

f100 = fib2(100)    # call it
f100                # write the result